1. Field of the Invention
The invention relates to a contact element for the electrically conductive connection of contact regions situated in opposite positions, and in particular to a contact element by which radio-frequency signals can be transmitted between two components, particularly two printed circuit boards, with as great a freedom from losses as possible. The invention also relates to a contact device having a plurality of such contact elements.
2. Description of Related Art
It is known for a connection to be made between two printed circuit boards by means of two co-axial insertion-type connectors which are solidly connected to the printed circuit boards and an adapter, the so-called “bullet”, which connects the two co-axial insertion-type connectors. This adapter allows an axial and radial compensation for tolerances and also allows tolerances on parallelism to be compensated for. Typical co-axial insertion-type connectors used for this purpose are SMP connectors, mini-SMP connectors and FMC connectors.
Alternatively, electric connections are also made between two printed circuit boards by means of spring-loaded contact pins of single-conductor and/or multi-conductor construction.
Also, there is known from U.S. Pat. No. 6,776,668 issued to Scyoc, et al., on Aug. 17, 2004, titled “LOW PROFILE COAXIAL BOARD-TO-BOARD CONNECTOR,” a co-axial contact element via is taught which radio-frequency signals are to be transmitted between two printed circuit boards. In this case a center conductor, in the form of a spring-loaded contact pin, acts as a signal conductor, while an outer conductor surrounding the center conductor performs the functions of a return conductor and of shielding for the center conductor. The outer conductor comprises a base body in sleeve form which is slotted more than once in the longitudinal direction. At its end-face, the unslotted end of the base body forms a point of contact to make contact with a contact-making region of one of the printed circuit boards. Displaceably guided on the base body is a sleeve of the outer conductor which at one end, at its end-face, forms a point of contact to make contact with a contact-making region on the other printed circuit board. A pre-loaded spring is supported between the base body and the sleeve. As the two printed circuit boards are being connected, both the head of the center conductor, which center conductor is in the form of a spring-loaded contact pin, and the sleeve of the outer conductor are displaced and thereby subject their respective springs to further pre-loading, whereby secure and reliable contact-making pressure can be produced in spite of any possible tolerances on the distance from one another of the contact-making regions of the printed circuit boards. Because the base body is slotted, it also has a certain flexibility in the lateral direction, what is intended to be achieved thereby being the ability to compensate even for relatively large degrees of non-parallelism between the two contact-making regions.
Also known is the use of simple resilient tongues as contact elements or as parts of contact elements. These have the advantage of being easy to construct and inexpensive to manufacture as, for example, stamped, punched or die-cut, and bent, components. At the same time, resilient tongues perform all the essential functions of contact elements of this kind, namely on the one hand the transmission of power or signals, and also the elastic deformation to obtain an adequate contact-making pressure at the points of contact and to compensate for tolerances on the attitude and position of the components to be connected. What is disadvantageous however is that, due to their principle, resilient tongues extend along an arcuate or angled path and the contact-making regions to be connected electrically are thus not connected in a direct line. The relatively great length of the resilient tongue goes hand in hand with a relatively high impedance and even inductance, which may have an adverse effect in particular on the quality of the transmission of radio-frequency signals.